A friend has emailed "I think your millipede is what I call cf. Trachypodoiulus niger. Certain identification of this group is not easy and requires specialist literature and close examination of some of the features from the specimen. Images do not show the necessary features such as genitalia."

I wouldn't call it anything but Julidae sp. - or perhaps rather Julida sp. (i.e. on the order-level - as I can't exclude Choeniulus palmatus which belongs to Blaniulidae which differ from Julidae in the arrangement of the ocelli [Julidae in a equilateral triangular field, Blaniulidae in a thin wedge, line - as in C. palmatus - or absent]). Julida are "in principle" impossible to identify without very close studies (especially of ther genitalia).